JP7126081B1 - Molten iron manufacturing method using electric furnace equipped with image device - Google Patents

Abstract

To ensure a stable supply of a cold iron source to a melting chamber. An electric furnace comprising a preheating chamber, a melting chamber, an extruder provided in the preheating chamber, and a video device for observing the inside of the melting chamber is used, and the cold iron source preheated in the preheating chamber is extruded. and a melting step of obtaining molten iron by melting the cold iron source supplied to the melting chamber by arc heat. A method for producing molten iron, wherein the amount of movement of the extruder and/or the time interval for moving the extruder is controlled based on the visual information obtained.

Description

The present invention relates to a method for producing molten iron from a cold iron source using an electric furnace equipped with an imaging device. In particular, the present invention is a molten iron melt that can observe how the cold iron source is supplied from the preheating chamber to the melting chamber, and based on this visual information, can control the supply conditions of the cold iron source to the melting chamber. related to the manufacturing method of

In the production of molten iron using an electric furnace, a cold iron source such as scrap is melted by arc heat to obtain molten iron. Conventionally, in order to reduce power consumption in electric furnaces, the method of preheating the cold iron source before melting with a burner using fossil fuel, etc.; A method of preheating using high-temperature exhaust gas generated during melting; a method of blowing coke into the melting chamber as an auxiliary heat source; and other methods are adopted.

For example, in Patent Document 1, in an electric furnace in which a preheating shaft and a melting chamber are directly connected, a cold iron source is continuously connected to the preheating shaft so as to maintain a state in which the cold iron source is continuously present in the melting chamber and the preheating shaft. Techniques have been disclosed for arc melting a source of cold iron in a melting chamber with a steady or intermittent supply. In the technique of Patent Document 1, the cold iron source preheated by high-temperature exhaust gas melts into the melted molten iron using an electric furnace that does not particularly require a device for conveying and supplying the cold iron source to the melting chamber. This effectively dissolves the cold iron source.

Further, for example, Patent Document 2 discloses an operation control system for an electric furnace, in which an input unit that accepts setting items that are operating conditions for electrorefining and setting items are input to a neural network, and based on the operation result estimated value A control system for an electric furnace is disclosed having a controller for performing electric furnace smelting.

Further, for example, Patent Document 3 discloses a method for producing molten metal by melting an iron source using arc melting equipment, wherein a state change is detected in the melting chamber when an arc discharge is generated. A supply speed adjustment step of adjusting the supply speed when supplying the iron source to the melting chamber based on the detection result of the detection step and the state change detection step. A method of manufacture is disclosed.

JP-A-10-292990 JP 2018-70926 A JP 2011-69606 A

However, as a result of investigation by the present inventors, the technique of Patent Document 1 basically feeds the cold iron source to the melting chamber continuously while gradually melting the cold iron source by preheating the cold iron source and its own weight. However, it was actually confirmed that the supply of the cold iron source was interrupted in the path from the preheating shaft to the melting chamber. This has been found to be due to unintended circumstances, for example, the cold iron source being over-preheated and stuck in large chunks, or gaps forming in the cold iron source tower. However, since the state of the cold iron source in the melting chamber cannot be directly observed with the technique of Patent Document 1, it was not possible to grasp the above unintended situation during operation. It was also found that such an irregular supply of the cold iron source increases power consumption in the electric furnace.

The technology of Patent Document 2 is an electric furnace operation control system that constructs a neural network that reflects the immediate state of the electric furnace and can estimate the end point carbon concentration of molten steel to be tapped with high accuracy. The data is the data photographed by the scrap charging device, that is, the cold iron source before being charged into the electric furnace. The temperature of the cold iron source differs before and after it is charged into the electric furnace, and the stacking method of each cold iron source changes after it is charged in the electric furnace. It cannot be said that the above technology is sufficient to provide a sufficient supply. Furthermore, although the above-described techniques are capable of controlling the end-point carbon concentration and temperature, they are still insufficient in terms of obtaining molten iron with high efficiency and low electric power consumption.

The technique of Patent Document 3 describes adjusting the supply speed when supplying the iron source to the melting chamber based on the result of the detection process, but regarding the movement of the cold iron source in the electric furnace However, it is not enough to provide a stable supply of cold iron sources.

The present invention has been made in view of the above circumstances, and is an electric furnace that can reliably supply a cold iron source to a melting chamber and obtain molten iron with high efficiency and low power consumption. An object of the present invention is to provide a method for producing molten iron.

As a result of repeated studies on a method that can solve the above problems, the present inventors have found that an electric furnace is equipped with a device (extruder) for conveying and supplying cold iron sources to the melting chamber, and the inside of the melting chamber A stable supply of cold iron source to the melting chamber can be ensured by providing an observable imaging device and optimizing the operating conditions of the extruder immediately based on the state of the melting chamber obtained from the imaging device. I found what I can do. It was also found that by stably supplying the cold iron source in this way, it is possible to prevent operational troubles and effectively reduce the power unit consumption in manufacturing.

The present invention has been made based on the above findings, and has the following gist.
1. A method for producing molten iron using an electric furnace equipped with a preheating chamber and a melting chamber,
The electric furnace further comprises an extruder provided in the preheating chamber and a video device for observing the inside of the melting chamber,
an extruding step of supplying the cold iron source preheated in the preheating chamber to the melting chamber by the extruder;
a melting step of obtaining molten iron in the melting chamber by melting the cold iron source supplied to the melting chamber by arc heat;
A method for manufacturing molten iron, wherein in the extrusion step, one or both of a movement amount of the extruder and a time interval for moving the extruder are controlled based on visual information obtained from the imaging device.

Here, in the present invention, the "movement amount of the extruder" means the movement distance of the extruder along the extrusion direction when the extruder moves once from the preheating chamber side to the melting chamber side. In addition, the "time interval for moving the extruder" means the interval from the time when the extruder starts moving one time (T0 _START ) to the time when the extruder starts moving the next time (T1 _START ). (see FIGS. 2A and 2B).

2. In the extrusion step, when the visual information obtained from the imaging device confirms that the cold iron source is not being supplied from the preheating chamber to the melting chamber, the increase in the movement amount and the time 2. The method for producing molten iron according to 1 above, wherein either one or both of the intervals are reduced.

3. 3. The molten iron according to 1 or 2 above, wherein in the extrusion step, either one or both of the increase in the movement amount and the reduction in the time interval are performed when the extrusion pressure of the extruder is 40 MPa or less. Production method.

ADVANTAGE OF THE INVENTION According to this invention, a cold iron source can be stably and reliably supplied to a melting chamber in an electric furnace. This leads to an increase in the melting efficiency of the cold iron source, an effective reduction in the power unit consumption, prevention of operational troubles, and the like, and produces exceptional industrial effects.

1 is a longitudinal sectional view of an electric furnace equipped with a video device used in one embodiment of the present invention; FIG. FIG. 2A is a conceptual diagram illustrating the amount of movement of the extruder and the time interval for moving the extruder, FIG. 2A shows the behavior of extrusion at a certain timing, and FIG. show.

Next, embodiments of the present invention will be specifically described.
The following embodiments show preferred examples of the present invention, and are not limited by these examples.

(Molten iron manufacturing method)
The method for producing molten iron of the present invention is a method using an electric furnace having a predetermined structure, and includes an extrusion step of supplying a cold iron source preheated in a preheating chamber to the melting chamber by an extruder, and a melting step of melting the cold iron source by arc heat to obtain molten iron, and may optionally further include other steps. Further, in the extrusion process of the present invention, the operating conditions of the extruder are controlled based on visual information obtained from a video device for observing the inside of the melting chamber.
By appropriately and timely controlling the operating conditions of the extruder based on the visual information in the melting chamber, the cold iron source can be stably and reliably supplied to the melting chamber, effectively reducing power consumption in the electric furnace. can be reduced to

[Electric furnace]
An electric furnace that can be suitably used in the present invention will be described in detail below with reference to the drawings.
The electric furnace 1 includes a melting chamber 2 which melts a cold iron source 15 by heat from an arc 18 to obtain molten iron 16, and a melting chamber 2 which preheats the cold iron source 15 and melts the preheated cold iron source 15 with an extruder 10. 2, and a video device 30 installed at an arbitrary position.

A cold iron source 15 as a raw material is loaded into a supply bucket 14 and transported to above a desired cold iron source supply port 19 via a traveling carriage 23 . Next, the cold iron source supply port 19 is opened to supply the cold iron source 15 to the preheating chamber 3 from above.
The cold iron source 15 supplied to the preheating chamber 3 is preheated by any method. For example, the production efficiency can be increased by preheating the cold iron source 15 by passing the hot exhaust gas generated in the melting chamber 2 to the preheating chamber 3 . Exhaust gas may be sucked through the duct 20 and passed through the preheating chamber 3 , and excess exhaust gas may be exhausted through the duct 20 .

A preheated cold iron source 15 is continuously supplied to the melting chamber 2 by the extruder 10 . The extruder 10 continues to push out the cold iron source 15 in the preheating chamber 3 into the melting chamber by repeatedly moving its tip toward the melting chamber. The supply amount and supply timing of the cold iron source 15 to the melting chamber 2 by the extruder 10 can usually be adjusted by the amount of movement of the extruder 10 and the time interval for moving the extruder 10 . The supply of the cold iron source 15 is accelerated as the amount of movement of the extruder 10 is increased or the time interval for moving the extruder 10 is shortened. In addition, from the viewpoint of operational efficiency, these moving amounts and time intervals are usually automatically operated after being initially set to certain values. However, in the present invention, as will be described in detail later, it is confirmed on the spot that the cold iron source 15 is being supplied to the melting chamber 2, and based on the confirmation result, the operating conditions of the extruder 10 are adjusted simultaneously. Control is essential.
Note that the extruder 10 usually has a cylinder structure.

The melting chamber 2 is partitioned by a furnace wall 4 and a furnace lid 5, and usually includes an electrode 6 for generating an arc 18 for heating, an oxygen blowing lance 7 for maintaining a desired high temperature state, and a carbon material. It is equipped with a blowing lance 8 and a burner 9 for locally heating cold spots. The cold iron source 15 supplied to the melting chamber 2 is melted by arc heat to become molten iron 16 and molten slag 17 . The obtained molten iron 16 can be tapped from the tapping port 12 by opening the tapping door 21 . Further, the molten slag 17 can be discharged from the slag discharge port 13 by opening the slag discharge door 22 .

The cold iron source 15 generally includes, but is not limited to, in-house scrap generated in ironworks, scrap generated in the city, and pig iron made by solidifying hot metal. In-house scrap generated at steelworks includes, for example, unsteady parts of slabs cast by continuous casting or ingot casting (parts generated at the start of casting and parts generated at the end of casting), rolling of steel materials such as steel strips, etc. There are crops that occur in Scraps generated in the market include recycled materials such as construction steel materials (H-beam steel, etc.), automobile steel materials, and cans. Pig iron obtained by solidifying molten pig iron is obtained by tapping and solidifying molten pig iron obtained from iron ore and coke as raw materials in a blast furnace such as a blast furnace.

The video device 30 is not particularly limited, and may be any device capable of capturing an image of an observation target, and normally includes a lens and a camera. It is preferable to flow the cooling gas at an arbitrary flow rate around the lens (not shown) installed at the tip of the imaging device 30 . By properly cooling the imaging device 30, it is possible to withstand the high temperature inside the electric furnace, and to prevent the field of view from being narrowed when slag or molten steel scatters. Cooling gases include air and inert gases such as nitrogen. Further, for example, when the imaging apparatus 30 is installed on the furnace wall 4, it is preferable that the furnace wall 4 is also cooled by water cooling or air cooling.
From the viewpoint of better grasping the behavior of the cold iron source 15 being pushed out from the preheating chamber 3 to the melting chamber 2, the video device 30 is preferably installed on the furnace wall 4 or the furnace lid 5 that defines the melting chamber 2. , more preferably on the furnace wall 4 . Also, from the same point of view as above, it is preferable to install at an appropriate height in the melting chamber 2 at which slag and molten steel are less likely to scatter. Although the installation method is not particularly limited, when the imaging device 30 is installed on the furnace wall 4, if the imaging device 30 is attached through a hole (not shown) made in the furnace wall 4, the lens can be installed in the melting chamber 2. The camera can be positioned outside the electric furnace 1 while being positioned, and it is possible to achieve both a clear visual field and simple operability. Images captured by the imaging device 30 are generally connected to a monitor and a recording device (both not shown) in an operation room operated by an operator via a cable (not shown).

[Extrusion process]
In the extrusion process of the present invention, the cold iron source 15 preheated in the preheating chamber 3 is extruded and supplied to the melting chamber 2 by the extruder 10 provided in the preheating chamber 3 . The supply amount and supply timing of the cold iron source 15 for one extrusion are governed by the amount of movement of the extruder 10 and the time interval for moving the extruder 10 . In normal operation, there are a plurality of setting patterns for the moving amount and time interval values according to the type of cold iron source and preheating conditions, and automatic operation is performed by adopting a suitable setting pattern. In the present invention, as a result of the visual information obtained from the imaging device 30, while it is confirmed that the cold iron source 15 is supplied into the melting chamber 2 without any problem, the setting pattern of the movement amount and/or the time interval can be controlled to continue automatic operation without changing

However, as described above, the supply of the cold iron source 15 may be delayed for some reason. Specifically, as the visual information from the video device 30, for example, the movement of the cold iron source 15 entering the melting chamber 2 becomes sluggish and intermittent, or it completely stops, or the molten iron 16 in the melting chamber 2 In some cases, it is confirmed that the interface does not rise to the desired position. In this way, when it is confirmed by the imaging device 30 that the cold iron source 15 is not supplied from the preheating chamber 3 to the melting chamber 2, the setting pattern of the movement amount and/or time interval of the extruder 10 is immediately set. can be changed and controlled. When setting the movement amount and/or time interval to different values, the automatic operation is temporarily switched to the manual setting, and when the good supply of the cold iron source 15 is confirmed again, the automatic operation is resumed with the normal setting pattern. do it.

Amount of Movement It is one of the features of the present invention to control whether or not to change the amount of movement of the extruder 10 based on the visual information obtained from the imaging device 30 . In particular, when it is confirmed by the image device 30 that the cold iron source 15 is not normally supplied, the movement amount is increased to push out the extruder 10 over a longer distance, thereby smoothing the cold iron source 15. should be promoted. For example, to intentionally move a cold iron source 15 of 1 ton, the displacement of the extruder 10 can be increased by about 10%.
The changed amount of movement may be used until the cold iron source 15 is supplied normally again. The displacement of the extruder 10 can be constantly monitored by a position sensor.

Time Interval It is also one of the features of the present invention to control whether or not to change the time interval for moving the extruder 10 based on the visual information obtained from the imaging device 30 . In particular, when it is confirmed by the video device 30 that the cold iron source 15 is not normally supplied, the time interval is reduced to push the extruder 10 more times within a certain period of time, thereby increasing the cold iron source 15. It is preferable to promote smooth movement of the For example, in order to intentionally move a cold iron source 15 of 1 ton, the time interval for moving the extruder 10 can be shortened by about 20%.
The changed time interval may be adopted until the cold iron source 15 is supplied normally again. The time intervals of the extruder 10 can also be constantly monitored by timers and position sensors.

Pressure The pressure on the extruder 10 can be measured at any time. Further investigation by the present inventors revealed that there is a correlation between the visual information from the imaging device 30 and the extrusion pressure when the extruder 10 moves toward the melting chamber 2 side. In other words, the visual information from the imaging device 30 indicates that the cold iron source 15 is not supplied normally. In this case, it was newly found that the extrusion pressure of the extruder 10 was 40 MPa or less.
The visual information from the imaging device 30 is primarily information about the surface of the cold iron source 15 that is present in the visual field of the imaging device 30 . Therefore, for example, it is difficult to confirm the state of the cold iron source 15 existing inside the tower of the cold iron source 15 from this surface by the image device 30, and the entire depth of the tower of the cold iron source 15 is moved. It is difficult to determine whether However, if the extrusion pressure applied to the extruder 10 is used as an indicator in addition to the visual information from the imaging device 30, the normal supply of the cold iron source 15 to the melting chamber 2 can be controlled more accurately. That is, when the cold iron source 15 is not normally supplied in the visual information from the imaging device 30 and the extrusion pressure of the extruder 10 is 40 MPa or less, as described above, the movement amount of the extruder 10 is It is preferred to increase and/or decrease the time interval over which the extruder 10 is moved.

[Dissolving process]
In the melting process of the present invention, molten iron is obtained in the melting chamber 2 by melting the preheated cold iron source 15 supplied to the melting chamber 2 by arc heat. A specific melting method is as described above for the electric furnace. In the present invention, the operating conditions of the extruder 10 are timely controlled during operation so as to smoothly supply the cold iron source 15 from the preheating chamber 3 to the melting chamber 2 while observing the inside of the melting chamber 2 using the imaging device 30. Therefore, power consumption required in the melting process can be reduced.

[Other processes]
Other processes include, for example, a preheating process and a tapping process.
In the preheating step, prior to the extrusion step, the cold iron source 15 can be preheated by any heating method to enhance the efficiency of the subsequent melting step. Moreover, as described above, if the high-temperature exhaust gas generated in the melting chamber 2 is used for the preheating process, the power consumption required for the preheating process can be reduced.
In the tapping process, the molten iron 16 accumulated in the melting chamber 2 can be taken out of the electric furnace 1 through the tapping port 12 after the melting process.

EXAMPLES The present invention will be specifically described below based on examples. In addition, the following examples show a preferable example of the present invention, and do not limit the present invention in any way. In addition, the following examples can be modified within the scope of the present invention, and such aspects are also included in the technical scope of the present invention.

In an electric furnace equipped with a melting chamber 2, a preheating chamber 3, an extruder 10, and a video device 30 installed in the melting chamber 2 shown in FIG. was melted to produce molten iron. Among the extrusion conditions described in Table 1, the amount of movement and the time interval are values that were set artificially, and the pressure was extruded with these set amounts of movement and the time interval, resulting in the extruder 10 is the value taken. The equipment specifications of this electric furnace are shown below.
Molten iron capacity of melting chamber: 130 tons Power: AC 50Hz
Transformer capacity: 75MVA
Number of electrodes: 3
The imaging device 30 was installed through a hole provided in the furnace wall 4 at a position 500 mm higher than the designed molten iron interface when 130 tons of molten iron was obtained. Along the outer surface of the video device 30, as cooling air, air prepared in the factory was flowed at a flow rate of 200 NL/min. In addition, a dryer system by heating was used for drying the air. Visual information (video) from the video device 30 was stored in a separate recording medium by extending a cable to the command room and the electrical control room where the electric furnace 1 was operated. A monitor was newly prepared in the control room so that the operator who operates the electric furnace 1 can directly monitor the image from the imaging device 30 . In addition, data on the amount of movement of the extruder 10, the time interval for moving the extruder 10, and the extrusion pressure were transferred to the electric control room so that these data and video information could be checked at the same time.

Conventional example 1
Conventional example 1 is an example in which the production method does not use an imaging device and is operated within the range of a normal power consumption rate.
The extruder (cylinder) was set to move 1,000 mm once at a certain timing, and the time interval of movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 58 MPa.
After 20 seconds, the cylinder was continuously pushed out with a movement amount of 1000 mm without changing the movement amount and time interval of the cylinder at the next timing, and the pressure applied to the cylinder was 64 MPa. Thus, one charge of molten iron was obtained without changing the extrusion conditions.
Although it is not possible to check the state of supply of the cold iron source because no video equipment is installed, in the experience of the operator, in Conventional Example 1, the cold iron source is supplied to the melting chamber at regular intervals and in a constant amount as expected. It was thought that As a result, the power unit consumption per charge was 333 kWh/t in the operation of the electric furnace.

Conventional example 2
Conventional Example 2 is an example of a manufacturing method that does not use a video device, in which the power consumption rate is higher than usual.
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 33 MPa, which was lower than that of Conventional Example 1.
Since the imaging device was not used, the reason why the pressure became lower than usual was not clarified, and without changing the amount of movement and time interval of the cylinder at the next timing, the amount of movement was 1000 mm after 20 seconds. When the cylinder was pushed out, the pressure on the cylinder remained low at 31 MPa. Thus, one charge of molten iron was obtained without changing the extrusion conditions. The dissolution time required to obtain one charge of molten iron was longer than the time assumed in the design.
Although it is not possible to check the supply state of the cold iron source because no video equipment is installed, in Conventional Example 2, the cold iron source is not supplied to the melting chamber as expected for some reason, and the cold iron source is efficiently supplied. It was assumed that it could not be dissolved. As a result, the power unit consumption per charge was 362 kWh/t, which was worse than that of Conventional Example 1.

Comparative Example A comparative example is an example in which the extrusion conditions were not controlled based on the visual information obtained from the imaging device in the manufacturing method using the imaging device.
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 34 MPa, which was lower than that of Conventional Example 1. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source did not move to the melting chamber and was stagnant.
Even though it was confirmed by the video device that the cold iron source was not normally supplied to the melting chamber, the movement amount continued after 20 seconds without changing the movement amount and time interval of the cylinder at the next timing. When extruding the cylinder at 1000 mm, the pressure on the cylinder remained low at 34 MPa. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source was still stagnant without moving to the melting chamber. Thus, one charge of molten iron was obtained without changing the extrusion conditions. The dissolution time required to obtain one charge of molten iron was longer than the time assumed in the design. As a result, the power unit consumption per charge was 347 kWh/t, which was worse than that of Conventional Example 1. Therefore, the overall evaluation was set to x (failed).

Invention Examples 1 to 6 are examples in which the extrusion conditions are controlled based on the visual information obtained from the imaging device in the manufacturing method using the imaging device.
Invention example 1
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 30 MPa, which was lower than that of Conventional Example 1. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source did not move to the melting chamber and was stagnant.
Therefore, the time interval for moving the cylinder at the next timing was shortened to 5 seconds. A set pattern in which the time interval was shortened to 5 seconds while the amount of movement of the cylinder was kept at 1000 mm was repeated several times until it was confirmed by the image device that the cold iron source started to be supplied normally. The pressure applied to the cylinder recovered to 58 MPa when it was confirmed that the cold iron source started to be supplied normally. After that, the time interval was temporarily returned to 20 seconds, but stagnation of the cold iron source was also confirmed (at this time, the cylinder pressure was 40 MPa or less), so the time interval was temporarily changed as described above. changed to 5 seconds. While repeating this operation, one charge of molten iron was obtained. As a result, the electric power unit consumption per charge was 327 kWh/t, which was better than that of Conventional Example 1. Therefore, the overall evaluation was ◯ (accepted).

Invention example 2
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 34 MPa, which was lower than that of Conventional Example 1. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source did not move to the melting chamber and was stagnant.
Therefore, the amount of movement of the cylinder at the next timing was increased to 1200mm. A setting pattern in which the time interval for moving the cylinder was kept at 20 seconds and the amount of movement was increased to 1200 mm was repeated several times until it was confirmed by the imaging device that the cold iron source started to be supplied normally. The pressure applied to the cylinder recovered to 62 MPa when it was confirmed that the cold iron source started to be supplied normally. After that, the movement amount was temporarily returned to 1000 mm, but similarly the stagnation of the cold iron source was confirmed (at this time, the cylinder pressure was 40 MPa or less). Changed to 1200mm. While repeating this operation, one charge of molten iron was obtained. As a result, the electric power unit consumption per charge was 329 kWh/t, which was better than that of Conventional Example 1. Therefore, the overall evaluation was ◯ (accepted).

Invention example 3
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 31 MPa, which was lower than that of Conventional Example 1. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source did not move to the melting chamber and was stagnant.
Therefore, the time interval for moving the cylinder at the next timing was shortened to 5 seconds, and the amount of movement of the cylinder was increased to 1200 mm. This setting pattern was repeated several times until it was confirmed on the imaging device that the cold iron source started to be supplied normally. The pressure applied to the cylinder recovered to 67 MPa when it was confirmed that the cold iron source started to be supplied normally. After that, the time interval was once returned to 20 seconds and the amount of movement was set to 1000 mm, but stagnation of the cold iron source was also confirmed (at this time, the cylinder pressure was 40 MPa or less). The time interval and travel were temporarily changed to 5 seconds and 1200 mm, respectively. While repeating this operation, one charge of molten iron was obtained. As a result, the electric power unit consumption per charge was 326 kWh/t, which was better than that of Conventional Example 1. Therefore, the overall evaluation was ◯ (accepted).

Invention example 4
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 32 MPa, which was lower than that of Conventional Example 1. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source was moving to the melting chamber, but the movement was sluggish.
Therefore, the amount of movement of the cylinder at the next timing was increased to 1200mm. A setting pattern in which the time interval for moving the cylinder was kept at 20 seconds and the amount of movement was increased to 1200 mm was repeated several times until it was confirmed by the imaging device that the cold iron source started to be supplied normally. The pressure applied to the cylinder recovered to 66 MPa at the time when it was confirmed that the cold iron source started to be supplied normally. After that, the movement amount was once returned to 1000 mm, but the phenomenon that the movement of the cold iron source was similarly dulled was confirmed (at this time, the cylinder pressure was 40 MPa or less). was temporarily changed to 1200 mm. While repeating this operation, one charge of molten iron was obtained. As a result, the electric power unit consumption per charge was 319 kWh/t, which was better than that of Conventional Example 1. Therefore, the overall evaluation was ◯ (accepted).

Invention example 5
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 35 MPa, which was lower than that of Conventional Example 1. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source was moving to the melting chamber, but the movement was sluggish.
Therefore, the time interval for moving the cylinder at the next timing was shortened to 5 seconds, and the amount of movement of the cylinder was increased to 1200 mm. This setting pattern was repeated several times until it was confirmed on the imaging device that the cold iron source started to be supplied normally. The pressure applied to the cylinder recovered to 71 MPa when it was confirmed that the cold iron source started to be supplied normally. After that, the time interval was once returned to 20 seconds and the movement amount was returned to 1000 mm, but the phenomenon that the movement of the cold iron source was similarly dulled was confirmed (at this time, the cylinder pressure was 40 MPa or less). Similarly, the time interval and the amount of movement were temporarily changed to 5 seconds and 1200 mm, respectively. While repeating this operation, one charge of molten iron was obtained. As a result, the electric power unit consumption per charge was 315 kWh/t, which was better than that of Conventional Example 1. Therefore, the overall evaluation was ◯ (accepted).

Invention example 6
The amount of movement set for one cylinder at a certain timing was 1000 mm, and the time interval for movement was 20 seconds. Moreover, the pressure applied to the cylinder when extruded under these conditions was 30 MPa, which was lower than that of Conventional Example 1. In fact, from the visual information obtained from the video equipment, it was confirmed that the cold iron source was moving to the melting chamber, but the movement was sluggish.
Therefore, the time interval for moving the cylinder at the next timing was shortened to 5 seconds. A set pattern in which the time interval was shortened to 5 seconds while the amount of movement of the cylinder was kept at 1000 mm was repeated several times until it was confirmed by the image device that the cold iron source started to be supplied normally. The pressure applied to the cylinder recovered to 69 MPa when it was confirmed that the cold iron source started to be supplied normally. After that, the time interval was once returned to 20 seconds, but the phenomenon of slowing down the movement of the cold iron source was also confirmed (at this time, the cylinder pressure was 40 MPa or less). Temporarily changed the interval to 5 seconds. While repeating this operation, one charge of molten iron was obtained. As a result, the electric power unit consumption per charge was 318 kWh/t, which was better than that of Conventional Example 1. Therefore, the overall evaluation was ◯ (accepted).

As is clear from Table 1, in the electric furnace, the supply of the cold iron source is unexpectedly controlled by controlling the extrusion conditions of the extruder in a timely manner based on the visual information in the melting chamber obtained from the video equipment. Even in this situation, the cold iron source continued to be well supplied to the melting chamber, and molten iron was obtained with high efficiency. As a result, the power unit consumption, which accounts for a large part of the manufacturing cost, can be greatly reduced, and the effect is very large.

According to the present invention, a cold iron source can be stably and reliably supplied to a melting chamber in an electric furnace, and the melting efficiency of the cold iron source can be enhanced.

1 electric furnace 2 melting chamber 3 preheating chamber 4 furnace wall 5 furnace lid 6 electrode 7 oxygen injection lance 8 carbon material injection lance 9 burner 10 extruder 12 outlet 13 slag outlet 14 supply bucket 15 cold iron source 16 molten iron 17 melting Slag 18 Arc 19 Cold iron source supply port 20 Duct 21 Door for hot water discharge 22 Door for slag discharge 23 Traveling carriage 30 Video device

Claims (3)

A method for producing molten iron using an electric furnace equipped with a preheating chamber and a melting chamber,
The electric furnace further comprises an extruder provided in the preheating chamber and a video device for observing the inside of the melting chamber,
an extruding step of supplying the cold iron source preheated in the preheating chamber to the melting chamber by the extruder;
a melting step of obtaining molten iron in the melting chamber by melting the cold iron source supplied to the melting chamber by arc heat;
A method for manufacturing molten iron, wherein in the extrusion step, one or both of a movement amount of the extruder and a time interval for moving the extruder are controlled based on visual information obtained from the imaging device. In the extrusion step, when the visual information obtained from the imaging device confirms that the cold iron source is not being supplied from the preheating chamber to the melting chamber, the increase in the movement amount and the time 2. The method for producing molten iron according to claim 1, wherein either one or both of the distance reduction is performed. 3. The molten iron according to claim 1 or 2, wherein in the extrusion step, when the extrusion pressure of the extruder is 40 MPa or less, either one or both of increasing the moving amount and reducing the time interval are performed. manufacturing method.

Images